Integration of pressure sensors into integrated circuit fabrication and packaging

ABSTRACT

A pressure sensor is integrated into an integrated circuit fabrication and packaging flow. In one example, a releasable layer is formed over a removable core. A first dielectric layer is formed. A metal layer is patterned to form conductive metal paths and to form a diaphragm with the metal. A second dielectric layer is formed over the metal layer and the diaphragm. A second metal layer is formed to connect with formed vias and to form a metal mesh layer over the diaphragm. The first dielectric layer is etched under the diaphragm to form a cavity and the cavity is covered to form a chamber adjoining the diaphragm.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of prior application Ser. No.14/141,875, filed Dec. 27, 2013, entitled, INTEGRATION OF PRESSURE ORINERTIAL SENSORS INTO INTEGRATED CIRCUIT FABRICATION AND PACKAGING, byKyu Oh Lee, (Attorney Docket No. 42P61081) the priority of which ishereby claimed.

TECHNICAL FIELD

The present description relates to the field of semiconductor packagesand, in particular, to integrating the formation or structure ofpressure or inertial sensors in the flow of producing semiconductorpackages.

BACKGROUND

Today's consumer electronics market frequently demands complex functionsrequiring very intricate circuitry. Scaling to smaller and smallerfundamental building blocks, e.g. transistors, has enabled theincorporation of even more intricate circuitry on a single die with eachprogressive generation. Semiconductor packages are used for protectingan integrated circuit (IC) chip or die, and also to provide the die withan electrical interface to external circuitry. With the increasingdemand for smaller electronic devices, semiconductor packages aredesigned to be even more compact and must support larger circuitdensity. For example, some semiconductor packages now use a corelesssubstrate, which does not include the thick resin core layer commonlyfound in conventional substrates. Furthermore, the demand for higherperformance devices results in a need for an improved semiconductorpackage that enables a thin packaging profile and low overall warpagecompatible with subsequent assembly processing.

Furthermore, for the past several years, microelectromechanical systems(MEMS) structures have been playing an increasingly important role inconsumer products. For example, MEMS devices, such as sensors andactuators, can be found in products ranging from inertial sensors forair-bag triggers in vehicles to micro-mirrors for displays in the visualarts industry and, more recently, in mobile applications such asaccelerometers for determining the orientation of the mobile device orair pressure sensors for altitude sensing. As these technologies mature,the demands on precision and functionality of the MEMS structures haveescalated. For example, optimal performance may depend on the ability tofine-tune the characteristics of various components of these MEMSstructures. Furthermore, consistency requirements for the performance ofMEMS devices (both intra-device and device-to-device) often dictate thatthe processes used to fabricate such MEMS devices need to be extremelysophisticated.

Although packaging scaling is typically viewed as a reduction in size,the addition of functionality in a given space is also considered.However, structural issues may arise when attempting to packagesemiconductor die with additional functionality also housed in thepackage. For example, the addition of packaged MEMS devices may addfunctionality, but ever decreasing space availability in a semiconductorpackage may provide obstacles to adding such functionality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a top plane and side cross-sectional view ofa pressure sensor that can be fabricated in accordance with anembodiment of the present invention.

FIGS. 2A and 2B illustrate a top plane and side cross-sectional view ofan accelerometer that can be fabricated in accordance with an embodimentof the present invention.

FIG. 3 illustrate a top plane view of a gyroscope that can be fabricatedin accordance with an embodiment of the present invention.

FIGS. 4A-4S illustrate cross-sectional views of various operations in amethod of fabricating a pressure sensor with a reference cavity inaccordance with an embodiment of the present invention.

FIGS. 5A-5K illustrate cross-sectional views of various operations in amethod of fabricating an inertial sensor in accordance with anembodiment of the present invention.

FIGS. 6A-6V illustrate cross-sectional views of various operations in aprocess flow for fabricating a pressure sensor horizontally beside aninertial sensor in accordance with an embodiment of the presentinvention.

FIGS. 7A-7K illustrate cross-sectional views of various operations in aprocess flow for fabricating inertial sensors stacked vertically inaccordance with an embodiment of the present invention.

FIG. 8 is a schematic diagram of a computer system, in accordance withan embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Semiconductor packages with pressure or inertial sensors are described.In the following description, numerous specific details are set forth,such as packaging architectures, in order to provide a thoroughunderstanding of embodiments of the present invention. It will beapparent to one skilled in the art that embodiments of the presentinvention may be practiced without these specific details. In otherinstances, well-known features, such as integrated circuit designlayouts, are not described in detail in order to not unnecessarilyobscure embodiments of the present invention. Furthermore, it is to beunderstood that the various embodiments shown in the Figures areillustrative representations and are not necessarily drawn to scale.

One or more embodiments described herein are directed to semiconductorpackages having one or more microelectromechanical systems (MEMS)structures incorporated therein. In one such embodiment, an air pressuresensor is fabricated in traditional (with or without a core) substrateprocessing layers. In other embodiments inertial sensors, such asaccelerometers or gyroscopes are fabricated in traditional or corelesssubstrate processing layers. Structures or devices described herein mayhave applications in one or more of mobile/consumer products which usetraditional or coreless substrate technology.

The described devices use three layers to process and as such can beeasily incorporated with any architecture that uses three or morelayers. Silicon nitride processing is used for forming the cavity of thediaphragm of the substrate. For inertial sensors, a reverse flow ispresented in which a magnet is attached at the end of the process, asneeded.

The same process flow may be used for both pressure sensors andmicrophones. These can be fabricated side-by-side (horizontalintegration) or one on top of the other (stacking or verticalintegration). Stacked formations are described using only one additionallayer for a total of four. Vertical combinations reduce the sensor areafootprint on the package.

Traditional or coreless substrate packaging technology is often used inpackaging dies for mobile devices. Air pressure or acoustic sensors areimportant for consumer mobile devices, providing microphones,altimeters, and barometers. Accordingly, in an embodiment, an airpressure sensor is fabricated in or via traditional or corelesssubstrate packaging technology. As a comparison, conventional, discreteair pressure sensors are typically relatively thick compared to asilicon die. The approach described provides for a much thinner sensorand mitigates the costs associated with separately fabricated airpressure sensors. The same applies to inertial sensors.

A variety of different embodiments are described herein. In oneembodiment, the sensor fabrication is horizontally integrated into thestandard substrate flow. The sensor may be a pressure sensor ormicrophone in one example, or an accelerometer or a gyroscope in anotherexample. In another embodiment, the sensor fabrication is horizontallyintegrated into the standard substrate flow without bumps. In anotherembodiment, both an accelerometer or gyroscope and a pressure sensor ormicrophone are horizontally integrated into the standard substratefabrication flow.

In another embodiment, the inertial sensors, such as accelerometers orgyroscopes are fabricated in a vertical package configuration. Theaccelerometers and gyroscopes can be fabricated vertically or stacked.The stacked configuration may be used to reduce the number of magnets. Asingle magnet may be placed over two inertial sensors and its magneticfield may be used for both sensors, depending on the particularimplementation. In another embodiment, the inertial sensors, such asaccelerometers or gyroscopes are fabricated in a vertical packageconfiguration without bumps.

In some embodiments, silicon nitride is used to form the cavitydiaphragm for the pressure sensor or microphone. In another embodiment,solder resist is used in combination with a patterned support mesh toclose a diaphragm cavity. For inertial sensors, pick and place tools maybe used in combination with die backing film (DBF) to attach a magnet onthe top side of a panel as compared to using embedded magnets.

As mentioned above, standard substrate processing flows and techniquesmay be used to form sensors of various kinds at the same time thatrouting layers and structures are being formed in another section of asubstrate. To do so new techniques may be used to form structures thatare used by the sensors. For an example, a diaphragm cavity may beetched into a dielectric and then be closed through the use of a supportmesh and solder resist lamination. The support mesh may be optimized toallow for ABF (Ajinomoto Build-up Film) etching under the support meshwhile still providing sufficient structure to support the laminatedsolder resist.

Another new technique is to use a die mount process to place and mount amagnet for use with an inertial sensor. A die backing film (DBF) similarto the current die mount process may alternatively be used to attach themagnet. This makes the magnet attachment process more similar to thestandard substrate package process. Alternatively, an adhesive film ortape may be used to secure the magnet, or the magnet may be thermallybonded to the package (e.g. by soldering) after the appropriatemetallization is applied. Sensors may be stacked vertically to allow onemagnet to actuate multiple sensors. Alternatively, multiple sensors maybe fabricated horizontally and use separate magnets to actuate eachdevice.

In typical substrate fabrication, standard organic build-up layers likeAjinomoto buildup film (ABF) or FR4 are used to form many of thestructures. This may be used to form some aspects of a sensor but maynot form an airtight seal for use in a diaphragm or reference cavity. Acopper via ring or silicon nitride may be used to form a hermeticallysealed package for the reference air pressure or any other purpose. Inone example air pressure sensor, the top surface of the sealed packageacts as a diaphragm and is the bottom electrode for the electrostaticsensing mechanism. In this arrangement, as the air pressure of theenvironment changes, sensed capacitance between the two electrodeschanges. Sufficient sensitivity may be achieved for the ranges ofinterest for consumer products. In one embodiment, a “continuous viaring” method is adaptable for other MEMS applications requiring areference air cavity or hermetic sealing of structures.

As an example of an air pressure sensor that can be fabricated usingtraditional or coreless substrate techniques, FIG. 1A shows a diagram ofa magnetically-actuated beam that may be fabricated in a patterned metallayer and used in conjunction with a pressure diaphragm fabricated asdescribed below. FIG. 1A is a top plan view diagram and FIG. 1B is acorresponding cross-sectional side view diagram of amagnetically-actuated resonant beam air pressure sensor, in accordancewith an embodiment of the present invention. However, a variety of otherdifferent types of pressure sensors may be fabricated of in metal layersusing the techniques described herein.

In this example, a magnetically-actuated resonant beam air pressuresensor 100 includes a diaphragm 102, resonant beams 104 and an embeddedmagnet 106. Resonant beams are actuated through the interaction of an ACcurrent with a permanent magnet. The diaphragm is deflected due to adifference in air pressure. This deflection will cause a displacementalong the Z axis. The displacement applies tension to the resonant beamsand increases the resonant frequency of the beams. The change inresonant frequency can be measured by other circuitry (not shown) andrelated to the air pressure, altitude, water depth, sound waves or anyother desired ambient pressure value. Although the magnet is embedded inthis example, it can be attached as an external component to the packagesubstrate after fabrication of the substrate, using any of theattachment mechanisms described above (e.g. using DBF, adhesive tape,solder, etc)

FIG. 2A is a top plan view diagram of an accelerometer 200 that can befabricated using traditional or coreless substrate techniques. A proofmass 202 acts as the inertial mass of the accelerometer and can befabricated in a patterned metal layer. The proof mass is suspended aboveand between a pair of magnets 204A, 204B that underlie respective coils206A, 206B. Each coil accommodates a see-saw movement about the X axis.The coils are each supported by a respective beam 208A, 208B.

The beams are anchored at each end by a respective anchor 210A, 210B,210C, 210D. The anchors provide mechanical support to the beams andelectrically connect the accelerometer circuit. Together each coil andits respective components, anchors and magnet form a detector arm 212A,212B.

FIG. 2B is a side cross-sectional view diagram of the accelerometershowing the magnets 204A, 204B and their relationship with the beam 208A(not visible), 208B. When exposed to an acceleration in the rightdirection, the proof mass moves and thereby induces a mechanical tensionin the beams increasing the resonant frequency of the beams. The changein resonant frequency can be measured by other circuitry (not shown) andrelated to the acceleration or change in direction of movement of thepackage.

As an example of gyroscope that can be fabricated using standardsubstrate techniques, FIG. 3 shows a top plan view diagram of aninductive gyroscope 301, in accordance with an embodiment of theinvention. As shown, a conductive drive coil 305 is disposed over asubstrate 304 and anchored to the substrate by conductive anchors 308A,308B, 308C, and 308D (e.g., Cu vias). The drive coil 305 is parallel tothe plane of the substrate 304 and can be formed in a patterned metallayer over a dielectric layer of the package substrate. The exemplarydrive coil has orthogonal segments 305A, 305B, 305C, and 305D formingone continuous conductive trace loop.

The drive coil is positioned over a magnet 310 and within its magnetic(B) field 311. The magnetic field 311 is perpendicular to the plane ofthe substrate 304 with the field 311 emanating away from, and returningto the substrate 304 at the north and south poles, respectively, asillustrated.

A drive signal generator 320 provides a time varying current (e.g.,sinusoidal) through the drive coil 305 generating an electromagneticforce 312 so that the drive coil 305 vibrates in one dimension relativeto the substrate 304. When an external angular rotation occurs about anaxis of rotation along an orthogonal dimension, the Coriolis forcecauses the vibrating drive coil to be displaced along a third dimension330, orthogonal to the first and second dimensions.

Sense coils 325A, 325B register a mutual inductance induced bydisplacement of the drive coil 305. A first pair of sense coils 325A,and 325B is positioned on opposite side of the drive coil and parallelto two of the drive coil segments. The sense coils are fastened to thesubstrate and do not vibrate. Mutual inductance within the sense coilsvaries as a function of drive coil displacement in both the x and ydimensions. The displacement of the coil in the x-dimension resultingfrom the external rotation with angular velocity Ω creates a timedependent flux across the sense coils, which in turn induces a voltageacross each sense coil that is correlated to the angular velocity Ω.Through signal processing in other circuitry (not shown), a differentialsignal derived from the voltage signals registered by each of the sensecoils may be used to determine the angular velocity Ω. Additional sensecoils 325C and 325D are formed parallel to the other two drive coilsegments 305A and 305B.

As described, the air pressure sensor in one embodiment is formed fromsuspended copper and solder resist features and from electrodes formedabove a reference cavity. The air pressure sensor compares the ambientair pressure with the reference air pressure in the cavity throughcapacitive coupling. The capacitive coupling (C) is determined by thedistance between the cavity diaphragm and the underlying structureformed above the reference cavity. The difference between ambient airpressure and reference air pressure is detected by an upwards ordownwards deflection of the diaphragm that covers the reference cavity.The sensed capacitance reflects the extent of downward or upwarddeflection of the diaphragm.

Alternatively, a magnetically-actuated resonant beam air pressure sensorcan be used. In this case, diaphragm deflection induces a tension in theresonant beams. The change in diaphragm height contributes to a changein beam length which translates into beam tension and an increased beamresonant frequency.

A packaged MEMS device, such as an air pressure sensor, may be housed ina variety of packaging options. The structure as depicted can be viewedas a completed package for a combined semiconductor die and sensor.However, for specific implementations, an array of external contacts(e.g., BGA contacts) may optionally be formed above or below thedepicted structure. The resulting structure may then be coupled to aprinted circuit board (PCB) or similar receiving surface.

Active surfaces of the packaged semiconductor die may include aplurality of semiconductor devices, such as but not limited totransistors, capacitors and resistors interconnected together by aninterconnection structure to form functional circuits. Usingsemiconductor die fabrication techniques, a device side of thesemiconductor die may be formed. The die may include semiconductors forany of a variety of different integrated circuit devices including butnot limited to a microprocessor (single or multi-core), a memory device,a chipset, a graphics device, an application specific integrated circuitaccording to several different embodiments. In another embodiment, morethan one die is embedded in the same package. For example, in oneembodiment, a packaged semiconductor die further includes a secondarystacked die. The first die may have one or more through-silicon viasdisposed therein (TSV die). The second die may be electrically coupledto the TSV die through the one or more through-silicon vias. In oneembodiment, both dies are embedded in or attached to a substrate.

FIG. 4A is a cross sectional side view diagram of a peelable core 400 asthe incoming starting material for producing a sensor, for example apressure sensor in a horizontal configuration. The pressure sensor canbe combined with any of a number of other micromachined or electroniccomponents such as transistors and circuitry. The incoming peelable corehas an organic carrier 402 at its center which is covered on both sideswith a laminated Cu foil 404 and a peelable Cu layer 406. Layer 406 isweakly adhered to the laminated Cu foil 404 so that it can be peeled offafter all the substrate fabrication processes are completed.

In FIG. 4B a dry film resist (DFR) is applied over the core and copperis deposited over the DFR pattern. After the DFR is removed a pattern ofcopper lands 408 remains. These lands may be used for connections toexternal devices after the substrate manufacturing process is completed.In FIG. 4C a build up layer 410 is deposited over the core and thecopper lands.

In FIG. 4D a diaphragm coating layer 412 is applied over the build-uplamination. The diaphragm coating may be fabricated from silicon nitrideor any of a variety of other materials including SiO2, SiON, SiCN, orSiCON. After the coating layer is applied, for example by deposition,then it may be etched in any desired pattern. In FIG. 4E laser etchingis used to create specific individual areas 414 for copper filling. Thesilicon nitride diaphragm coating is formed in any desired pattern.These layers may include routing layers for electronic devices ormicromachined layers such as beams, coils, or weights for any of varietyof different sensors.

In FIG. 4F a second metal layer is applied over the diaphragm layer. Thesecond metal layer 416 is applied over the buildup layer and into thevalleys 414 that were formed by etching. This copper pattern may be usedfor routing layers as well as for connections to vias that are formed inother layers within the resulting die. In FIG. 4E valleys 414 may belaser etched through to the core 406. These valleys may be filled asdesired to form vias 418 that extend from the outermost layer of the diedown to the core 406. A pattern of copper lines 416 may be applied overthese vias to make appropriate connections to various other vias. Inaddition this routing layer may form appropriate components of themicromachined structures shown for example in FIGS. 1, 2 and 3, such asbeams, coils, masses, and meshes.

In FIG. 4G a second dielectric layer 420 is formed over the first metallayer 416 and a second metal layer 422 is formed over the seconddielectric layer 420. The second metal layer may include metal meshes,routing layers and other components.

In FIG. 4H a plasma mask 424 is applied on both top and bottom sides ofthe structure. Buildup layer etching 426 may then be used to remove thebuildup layers in appropriate locations. As shown in FIG. 4H afteretching there is a lower mesh layer 428 formed from the first copperlayer and an upper mesh layer 430 formed from the second copper layer.In other locations of the substrate routing layers and other parts ofthe device may be protected by the plasma mask 424. These layers may notbe affected by the etching process. The metal mesh layers 428 and 430provide enough structure to support the layers that will be appliedabove and yet still allow for ambient access to a pressure sensordiaphragm or for generating various fields.

In FIG. 4I a solder resist pattern 432 is formed over the metal meshlayers. The metal mesh is sufficiently dense to support the solderresist pattern that is applied over the metal mesh.

In FIG. 4J a polymer film 434 such as PET (Polyethylene Terephthalate)is applied over the solder resist pattern by lamination or any otherdesired way. This polymer film 434 will protect the solder resist duringother processes. In FIG. 4K the peelable carrier is removed from thestructure after the structure has been built up.

FIG. 4K shows the lower half of the substrate and layers that have beenformed after the peelable Cu is etched away. The two halves of thestructure are de-paneled from the temporary cores removing the carrierand the upper half of the structure. This allows for access to thebackside of the die from above. A plasma mask 436 is applied over theback side of the structure 438 after which a buildup etching process 440is applied to the back side of the structure. The buildup etchingremoves a portion of the original lamination 410 that was applied overthe carrier. This creates a cavity 442 as shown in FIG. 4L.

The cavity may be lined with some sort of sealant for example 444silicon nitride. The silicon nitride coating is an air tight coating ora water tight coating for the pressure sensor depending on theparticular application. While silicon nitride is shown, other materialsmay also be used to seal the cavity 442 such as SiO2, SiON, SiCN, SiCON.

In FIG. 4M the cavity is covered with a cover 446 made of any desiredmaterial. In one example solder resist is patterned over the cavity andused as a cover. In another example a thin metal sheet is used as acover.

In FIG. 4N a silicon nitride coating 448 is applied over the solderresist pattern to protect it from the environment and to seal it airtight.

In FIG. 4O a dry film resist (DFR) 450 is patterned over the back sideof the structure to cover the diaphragm area. This allows then in FIG.4P for the silicon nitride layer 448 to be removed around the diaphragm.In FIG. 4Q the dry film resist may be stripped off. And in FIG. 4R thePET film on the front side of the structure may also be removed.

Finally in FIG. 4S solder bumps 454 are applied to contact pads in thestructure which connect through vias to the first and second metallayers. These also allow for connections to the diaphragm cavity 442 andthe completed pressure sensor 456. The pressure sensor responds tochanges in pressure by bending the diaphragm as explained above.

FIG. 5A is a side cross-sectional diagram that shows an example of theuse of an incoming peelable core 500 for use in fabricating an inertialsensor such as an accelerometer or a gyroscope. The inertial sensor maybe fabricated using conventional substrate processing techniques. Theincoming peelable core has an organic carrier 502 at its center which iscovered on both sides with a laminated Cu foil 504 and a peelable Culayer 506. Layer 506 is weakly adhered to the laminated Cu foil 504 sothat it can be peeled off after all the substrate fabrication processesare completed.

In FIG. 5B a dry film resist (DFR) pattern is used to apply copperplating according to a specific intended pattern. A pattern of lands 508for routing layers and connections are formed on both sides of the coreover the peelable Cu layer 506. In FIG. 5C a buildup layer 510 islaminated over the copper plating. In FIG. 5D laser etching is used toform valleys 512 in the buildup lamination. In FIG. 5E copper is appliedinto the valleys 512 to form vias 514 and a second metal layer 516 isapplied over the buildup. The second metal layer may be in the form of awire mesh and may also include routing layers as desired to connect themesh with the vias and any other components that are to be formed.

In FIG. 5F the operations of depositing buildup and patterning metalover the buildup are repeated with a second layer of dielectric 518 anda second metal layer 520 to form a second mesh pattern over thedielectric and over the first mesh.

In FIG. 5G a plasma mask 522 is applied on both sides of the structureand buildup etching 524 is applied to the structure. The metal maskdetermines which areas will be etched and the buildup in the exposedarea is completely removed. This provides for two layers of metal mesh516, 520 with no intervening materials. However, dielectrics remain inareas that were not exposed to the etching process.

In FIG. 5H a solder resist pattern 526 is applied over the etched areasto protect the metal mesh from other processes and to provide astructure for the sensor system. In FIG. 5I, the peelable Cu in the corehas been removed to separate the top and bottom substrate portions oneither side of the core, and the top substrate portion is retained.

In FIG. 5J the first dielectric layer has been de-paneled from thesupporting substrate. The solder bumps 528 are applied over the vias toconnect external components to the first and second mesh layers afterthe peelable Cu in the core has been removed to separate the top andbottom substrate portions on either side of the core. Any of a varietyof other electrical technologies may be used instead of solder bumps toconnect external components depending on the particular implementation.In FIG. 5K a magnet 532 has been placed over the first and second meshlayers for use as described above in building an inertial sensor.

FIG. 6A is a side cross-sectional diagram that shows an example of howan inertial and a pressure sensor may be fabricated in a horizontal or aside-by-side configuration using common processes in a singlefabrication process flow.

In FIG. 6A, a peelable core 600 has an inner organic carrier 602, anouter Cu film 604 and a peelable Cu layer 606 over the outer Cu film604. In FIG. 6B a first metal pattern 608 is formed over the peelable Culayer for example using photoresist patterning, copper metal deposition,and etching.

In FIG. 6C a first buildup layer 610 is laminated over the copperpattern layers 608. In FIG. 6D a diaphragm coating 612 is applied overthe buildup lamination 610. As mentioned above, the diaphragm coatingmay be silicon nitride or other materials such as SiO2, SiON, SiCN, orSiCON.

FIG. 6E shows a dry film resist patterned over portions of the buildupand coating structure. The dry film resist 614 masks some of thediaphragm layer 612. In FIG. 6F after etching the diaphragm layer isremoved over portions of the die. The diaphragm layer is removed fromthe portion which is to be used for the inertial sensor and remains overthe portion that is to be used for the pressure sensor. In this examplethe inertial sensor is to be formed on the right hand side and thepressure sensor is to be formed on the left hand side of the structureas shown in FIG. 6F. In FIG. 6G the dry film resist is removed leavingthe diaphragm coating in only some parts of the structure.

In FIG. 6H laser etching forms valleys 616 in appropriate portions ofthe structure and in FIG. 6I these valleys are filled with copper toform vias 618 and a second copper layer 620 is patterned over the viasand the remaining buildup layer. In the case of the inertial sensor amesh is formed by the second copper layer for use with the inertialsensor.

In FIG. 6I an additional dielectric buildup layer 622 is applied overthe first dielectric layer and the second metal layer with the mesh. Athird metal layer 624 is applied over the dielectric. In FIG. 6K aplasma mask 626 is patterned over the structure to protect areas of thebuildup layer and the remainder of the buildup layer is etched using anetch process 628 through the openings in the mask. This removes thebuildup material for the inertial sensor and for the pressure sensor.

In FIG. 6L solder resist 630 is patterned over the structure to form astructure for the interconnection layer of the device. The solder resistis patterned conventionally using for example photolithography or screenprinting. In FIG. 6M a PET film 632 is laminated over all the solderresist to cover the top and bottom sides of the structure and protectthe photoresist.

In FIG. 6N the two opposite side are de-paneled from the carrier by isremoving the peelable carrier. This separates the top and bottomsubstrate portions on either side of the core . . . . In the illustratedexample, the top half of the structure is removed for processingseparately. The lower half of the structure remains and the back side ofthis structure is facing toward the top as shown in the drawings. Asecond plasma mask 636 is then applied over the back side of thestructure. This exposes a portion of the pressure sensor for buildupetching 638.

In FIG. 6O the etched out cavity 640 for the pressure sensor is coatedin a sealant such as silicon nitrite 642. In FIG. 6P the cavity iscovered with any suitable material 644 such as solder resist as in theexample of FIG. 4M. Alternatively a thin metal sheet can be used tocover the cavity. In FIG. 6Q the solder resist is covered with a siliconnitride coating 646 to seal the cavity.

In FIG. 6R a dry photoresist 648 is patterned over the backside of thestructure. The dry photoresist protects the pressure sensor cavity butcompletely exposes the inertial sensor and all other areas on thebackside of the structure. In FIG. 6S the silicon nitride layer isetched so that it remains only underneath the dry photoresist 648. InFIG. 6T the DFR film is stripped from over the pressure sensor cavity640.

In FIG. 6U a solder ball 642 connection is applied to the front side ofthe structure after the PET film is removed to connect the pressuresensor and the inertial sensor to the external components. In FIG. 6V amagnet 644 is placed over the inertial sensor area to allow the inertialsensor to detect changes in acceleration or direction as is describedabove.

FIG. 7A is a cross-sectional side view diagram that shows a process flowfor fabricating an inertial sensor in a vertical configuration. In theexample of FIG. 7A an incoming peelable core 700 has a carrier 702, alaminated Cu foil 704 and a peelable Cu layer 706. Two inertial sensorsmay be stacked on top of each other and constructed in a streamlinedprocess as shown herein.

In FIG. 7B a dry film resist is patterned over the peelable Cu layer 706and used to deposit a copper connection and routing layer 708. The dryfilm resist is removed revealing the copper patterning. The copperpatterning is then covered with a buildup layer 710 to serve as adielectric and to isolate the copper layers. In FIG. 7D laser etching isused to form valleys 712 through the buildup. In FIG. 7E a second copperpattern 714 is plated over the buildup to form a first copper routingand mesh layer. The mesh layer is formed over the buildup layer whichprovides a support for the formation of the metal mesh 714.

In FIG. 7F an additional buildup layer 716 is formed over the firstcopper pattern and a second copper mesh layer 718 is formed over thesecond buildup layer. This provides the two layers of metal mesh thatare used in the inertial sensors as described herein. In FIG. 7G a thirdbuildup layer 720 is applied over the second metal mesh layer and athird metal mesh layer 722 is patterned and formed over the thirdbuildup layer.

In FIG. 7H a plasma mask 724 is positioned over the entire structure.The plasma mask protects most of the structure while buildup layeretching 726 is applied to remove the buildup layer in the locationswhere the inertial sensors are to be formed. As shown in FIG. 7H thebuildup layer is removed all the way from the third metal mesh layerdown to the first metal plating 708 right above the peelable Cu layer706 in the core.

In FIG. 7I a solder resist pattern 730 is formed over the metal meshlayers. The solder resist pattern may be patterned to expose areas 732for the formation of electrical connections. The exposed areas may takeany particular form depending upon the type of connection that is to beused. The solder resist may be covered with a PET film for protectionduring later processes. The PET film 732 may be removed before thedevice is completed.

In FIG. 7J the carrier is removed thus separating the top and bottomsubstrate portions on either side. Only the top portion remains in FIG.7J, whereas the bottom portion is removed and processed separately. Inthe remaining top portion, exposed areas 732 are filled with solder oranother conductor such as copper. Solder balls 734 are attached atappropriate locations to connect the inertial sensors to externalcomponents such as power supplies or signal processing circuits. Finallyin FIG. 7K a magnet is placed over the metal mesh layers. The magnet 736is used to induce a field that operates on the sensor metal structuresto produce an electrical signal in response to inertial events.

The packaged semiconductor die may, in an embodiment, be a fullyembedded semiconductor die. As used in this disclosure, “fully embedded”means that an active surface and the entire sidewalls of thesemiconductor die are in contact with an encapsulating film (such as adielectric layer) of a substrate, or at least in contact with a materialhoused within the encapsulating film. Said another way, “fully embedded”means that all exposed regions of an active surface and the exposedportions of the entire sidewalls of the semiconductor die are in contactwith the encapsulating film of a substrate. However, in such cases, thesemiconductor die is not “surrounded” since the backside of thesemiconductor die is not in contact with an encapsulating film of thesubstrate or with a material housed within the encapsulating film. In afirst embodiment, a back surface of the semiconductor die protrudes fromthe global planarity surface of the die side of a substrate. In a secondembodiment, no surface of the semiconductor die protrudes from theglobal planarity surface of the die side of a substrate.

In contrast to the above definitions of “fully embedded and surrounded”and “fully embedded,” a “partially embedded” die is a die having anentire surface, but only a portion of the sidewalls, in contact with anencapsulating film of a substrate (such as a coreless substrate), or atleast in contact with a material housed within the encapsulating film.In further contrast, a “non-embedded” die is a die having at most onesurface, and no portion of the sidewalls, in contact with anencapsulating film of a substrate (such as a traditional or corelesssubstrate), or in contact with a material housed within theencapsulating film.

As mentioned briefly above, an array of external conductive contacts maysubsequently be formed. In an embodiment, the external conductivecontacts couple the formed substrate to a foundation substrate. Theexternal conductive contacts may be used for electrical communicationwith the foundation substrate. In one embodiment, the array of externalconductive contacts is a ball grid array (BGA). In other embodiments,the array of external conductive contacts is an array such as, but notlimited to, a land grid array (LGA) or an array of pins (PGA).

Embodiments of the present invention may be suitable for fabricating asystem on a chip (SOC), e.g., for a smartphone or a tablet. In anembodiment, an air pressure sensor is integrated and fabricated in aBBUL packaging fab. The same backend processing used for existingtraditional or coreless substrate fabrication and packaging may be usedas a base flow. Alternatively, the process flow for die integration withMEMS may be applicable to other packaging substrate technologies.

FIG. 8 illustrates a computing device 1000 in accordance with oneimplementation of the invention. The computing device 1000 houses aboard 1002. The board 1002 may include a number of components, includingbut not limited to a processor 1004 and at least one communication chip1006. The processor 1004 is physically and electrically coupled to theboard 1002. In some implementations the at least one communication chip1006 is also physically and electrically coupled to the board 1002. Infurther implementations, the communication chip 1006 is part of theprocessor 1004.

Depending on its applications, computing device 1000 may include othercomponents that may or may not be physically and electrically coupled tothe board 1002. These other components include, but are not limited to,volatile memory (e.g., DRAM) 1008, non-volatile memory (e.g., ROM) 1009,flash memory (not shown), a graphics processor 1012, a digital signalprocessor (not shown), a crypto processor (not shown), a chipset 1014,an antenna 1016, a display 1018 such as a touchscreen display, atouchscreen controller 1020, a battery 1022, an audio codec (not shown),a video codec (not shown), a power amplifier 1024, a global positioningsystem (GPS) device 1026, a compass, accelerometer, a gyroscope andother inertial sensors 1028, a speaker 1030, a camera 1032, and a massstorage device (such as hard disk drive, or solid state drive) 1010,compact disk (CD) (not shown), digital versatile disk (DVD) (not shown),and so forth). These components may be connected to the system board1002, mounted to the system board, or combined with any of the othercomponents.

The communication chip 1006 enables wireless and/or wired communicationsfor the transfer of data to and from the computing device 1000. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 1006 may implementany of a number of wireless or wired standards or protocols, includingbut not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+,HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, Ethernetderivatives thereof, as well as any other wireless and wired protocolsthat are designated as 3G, 4G, 5G, and beyond. The computing device 1000may include a plurality of communication chips 1006. For instance, afirst communication chip 1006 may be dedicated to shorter range wirelesscommunications such as Wi-Fi and Bluetooth and a second communicationchip 1006 may be dedicated to longer range wireless communications suchas GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.

In some implementations, any one or more of the inertial sensors 1028 ofFIG. 8, may be produced or implemented as described herein. There may bemultiple pressure or inertial sensor dies. These dies may includecircuitry for other functions shown as discrete dies in FIG. 8. Thepressure sensor may be used as a microphone, an altimeter, or barometer,depending on the particular implementation. The term “processor” mayrefer to any device or portion of a device that processes electronicdata from registers and/or memory to transform that electronic data intoother electronic data that may be stored in registers and/or memory.

In various implementations, the computing device 1000 may be a laptop, anetbook, a notebook, an ultrabook, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, the computingdevice 1000 may be any other electronic device that processes data.

Embodiments may be implemented as a part of one or more memory chips,controllers, CPUs (Central Processing Unit), microchips or integratedcircuits interconnected using a motherboard, an application specificintegrated circuit (ASIC), and/or a field programmable gate array(FPGA).

References to “one embodiment”, “an embodiment”, “example embodiment”,“various embodiments”, etc., indicate that the embodiment(s) of theinvention so described may include particular features, structures, orcharacteristics, but not every embodiment necessarily includes theparticular features, structures, or characteristics. Further, someembodiments may have some, all, or none of the features described forother embodiments.

In the following description and claims, the term “coupled” along withits derivatives, may be used. “Coupled” is used to indicate that two ormore elements co-operate or interact with each other, but they may ormay not have intervening physical or electrical components between them.

In the following description and claims, the terms “chip” and “package”are used interchangeably to refer to any type of microelectronic,micromechanical, analog, or hybrid small device that is suitable for usein a computing device.

As used in the claims, unless otherwise specified, the use of theordinal adjectives “first”, “second”, “third”, etc., to describe acommon element, merely indicate that different instances of likeelements are being referred to, and are not intended to imply that theelements so described must be in a given sequence, either temporally,spatially, in ranking, or in any other manner.

The drawings and the forgoing description give examples of embodiments.Those skilled in the art will appreciate that one or more of thedescribed elements may well be combined into a single functionalelement. Alternatively, certain elements may be split into multiplefunctional elements. Elements from one embodiment may be added toanother embodiment. For example, orders of processes described hereinmay be changed and are not limited to the manner described herein.Moreover, the actions of any flow diagram need not be implemented in theorder shown; nor do all of the acts necessarily need to be performed.Also, those acts that are not dependent on other acts may be performedin parallel with the other acts. The scope of embodiments is by no meanslimited by these specific examples. Numerous variations, whetherexplicitly given in the specification or not, such as differences instructure, dimension, and use of material, are possible. The scope ofembodiments is at least as broad as given by the following claims.

The following examples pertain to further embodiments. The variousfeatures of the different embodiments may be variously combined withsome features included and others excluded to suit a variety ofdifferent applications. Some embodiments pertain to a method. In oneexample, a diaphragm is formed by depositing a metal over a firstdielectric layer. A second dielectric layer is formed over thediaphragm. A metal mesh layer is formed over the second dielectric. Thefirst dielectric layer is etched under the diaphragm to form a cavity.The cavity is lined with a sealing layer. The cavity is covered to forma chamber adjoining the diaphragm, and the cover is sealed against thecavity.

Further embodiments include finishing the substrate with attachmentbumps coupled to vias formed in the first dielectric layer andelectrically coupled to the diaphragm. Further embodiments includeforming metal vias to the diaphragm through the second dielectric layerduring forming the metal mesh. In further embodiments forming a metalmesh comprises patterning a photoresist, depositing a metal film andremoving the photoresist to form a mesh pattern.

In further embodiments etching the first dielectric layer comprisesde-paneling the first dielectric layer from a supporting substrate toexpose the first dielectric layer, applying a hard mask over the firstdielectric layer and etching the dielectric through the mask. In furtherembodiments the sealing layer comprises silicon nitride.

Some embodiments pertain to a pressure sensor in an integrated circuitdie, the pressure sensor includes a metal sensor diaphragm, a dielectricover the diaphragm, a metal mesh over the dielectric, a cavity under themetal sensor diaphragm, a sealing layer lining the cavity, and a coverover the cavity to form a chamber adjoining the diaphragm so thatmovement of the sensor diaphragm is sensed by the metal mesh.

Further embodiments include attachment bumps in the die to connect to anexternal electrical potential, the attachment bumps being connected tothe metal mesh through vias in the die. In further embodiments, themetal vias extend through the dielectric.

Some embodiments pertain to a computing system with a processor, amemory to store instructions for execution by the processor, and apressure sensor. The pressure sensor in the integrated circuit die ofthe computing system includes a metal sensor diaphragm, a dielectricover the diaphragm, a metal mesh over the dielectric, a cavity under themetal sensor diaphragm, a sealing layer lining the cavity, and a coverover the cavity to form a chamber adjoining the diaphragm so thatmovement of the sensor diaphragm is sensed by the metal mesh.

Some embodiments pertain to a method of forming a pressure sensor in anintegrated circuit die. The method includes forming a releasable layerover a removable core, forming a first dielectric layer over thereleasable layer, patterning a metal layer over the first dielectriclayer to form conductive metal paths and to form a diaphragm with thedeposited metal, forming a second dielectric layer over the metal layerand the diaphragm, forming vias through the second dielectric layer,patterning a second metal layer to connect with the formed vias and toform a metal mesh layer over the diaphragm, releasing the removable corefrom the first dielectric layer using the releasable layer, etching thefirst dielectric layer under the diaphragm to form a cavity, lining thefirst dielectric layer and the cavity with a sealing layer, covering thecavity to form a chamber adjoining the diaphragm, and sealing the coveragainst the cavity.

Further embodiments include finishing the substrate with attachmentbumps coupled to vias formed in the first dielectric layer andelectrically coupled to the diaphragm. In further embodiments formingvias further comprises forming metal vias to the diaphragm through thesecond dielectric layer. In further embodiments patterning the secondmetal layer comprises patterning a photoresist, depositing a metal filmand removing the photoresist to form a mesh pattern. In furtherembodiments etching the first dielectric layer comprises applying a hardmask over the first dielectric layer and etching the dielectric throughthe mask. In further embodiments the sealing layer comprises siliconnitride.

Some embodiments pertain to a pressure sensor in an integrated circuitdie. The pressure sensor includes a first patterned metal layer to formconductive metal paths of the integrated circuit and to also form adiaphragm of the pressure sensor, a second dielectric layer over themetal layer and the diaphragm, a second metal layer over dielectriclayer and the first patterned metal layer to connect with the formedvias and to form a metal mesh layer over the diaphragm, a firstdielectric layer under the first metal layer and removed under thediaphragm to form a cavity, a cover under the cavity to form a diaphragmchamber, and vias through the second dielectric layer to connect themetal diaphragm and the metal mesh to external components.

In further embodiments the chamber is sealed with silicon nitride. Infurther embodiments the metal paths are coupled to other circuitry inthe integrated circuit die to relate the diaphragm movement to apressure.

Some embodiment pertain to a method of forming an inertial sensor in anintegrated circuit die that includes forming a releasable layer over aremovable core, patterning a first metal layer over the releasablelayer, forming a first dielectric layer over the first metal layer,forming a diaphragm coating layer over a portion of the first dielectriclayer, forming vias through the second dielectric layer, patterning ametal layer over the dielectric layer to form conductive metal paths andto connect to the diaphragm layer, forming a second dielectric layerover the metal layer and the diaphragm, patterning a second metal layerto form a metal mesh over the diaphragm and coils of an inertial sensorand to connect with the formed vias, releasing the removable core fromthe first dielectric layer using the releasable layer, etching the firstdielectric layer under the diaphragm to form a cavity, lining the firstdielectric layer and the cavity with a sealing layer, covering thecavity to form a chamber adjoining the diaphragm, sealing the coveragainst the cavity, attaching a magnet over the coils of the inertialsensor, and finishing the substrate with attachment bumps coupled tovias formed in the first dielectric layer and electrically coupled tothe diaphragm.

In further embodiments forming the diaphragm coating comprisesdepositing a silicon nitride coating. In further embodiments forming thediaphragm coating comprises patterning the silicon nitride coating usingdry photoresist, etching the photoresist, and stripping the dryphotoresist. In further embodiments forming vias further comprisesforming metal vias to the diaphragm through the second dielectric layer.In further embodiments wherein patterning the second metal layercomprises patterning a photoresist, depositing a metal film and removingthe photoresist to form a mesh pattern. In further embodiments etchingthe first dielectric layer comprises applying a hard mask over the firstdielectric layer and etching the dielectric through the mask. In furtherembodiments the sealing layer comprises silicon nitride.

Some embodiments pertain to an inertial sensor in an integrated circuitdie. The sensor includes a first patterned metal diaphragm layer, afirst dielectric layer over the first metal layer, a diaphragm coatinglayer over a portion of the first dielectric layer, a second patternedmetal layer over the first dielectric layer to form conductive metalpaths and to connect to the diaphragm layer, a second dielectric layerover the second patterned metal layer and the diaphragm, a thirdpatterned metal layer forming a metal mesh over the diaphragm and coilsof an inertial sensor and connected with the formed vias, a cavity inthe first dielectric layer under the diaphragm forming a cavity, asealing layer lining the cavity, a cover over the cavity forming achamber adjoining the diaphragm, and a magnet over the coils of theinertial sensor.

In further embodiments the inertial sensor further comprises a mass nearthe coils so that movement of the mass affects an alternating current inthe coils.

Further embodiments include vias through the second dielectric layer toconnect the metal diaphragm layer and the coils of the inertial sensorto other circuitry of the integrated circuit die.

Some embodiments pertain to a computing system that includes aprocessor, a memory to store instructions for execution by theprocessor, and an inertial sensor in an integrated circuit die of thecomputing system. The sensor includes a first patterned metal diaphragmlayer, a first dielectric layer over the first metal layer, a diaphragmcoating layer over a portion of the first dielectric layer, a secondpatterned metal layer over the first dielectric layer to form conductivemetal paths and to connect to the diaphragm layer, a second dielectriclayer over the second patterned metal layer and the diaphragm, a thirdpatterned metal layer forming a metal mesh over the diaphragm and coilsof an inertial sensor and connected with the formed vias, a cavity inthe first dielectric layer under the diaphragm forming a cavity, asealing layer lining the cavity, a cover over the cavity forming achamber adjoining the diaphragm, and a magnet over the coils of theinertial sensor.

Some embodiments pertain to a method of forming an inertial sensor in anintegrated circuit die that includes forming a releasable layer over aremovable core, patterning a first metal layer over the releasablelayer, forming a first dielectric layer over the first metal layer,patterning a second metal over the dielectric layer to form coils of aninertial sensor and to connect to the first metal layer, forming viasthrough the first dielectric layer, forming a second dielectric layerover the second metal layer, patterning a third metal layer to formfurther coils of the inertial sensor and to connect with the formedvias, releasing the removable core from the first dielectric layer usingthe releasable layer, and attaching a magnet over the coils of theinertial sensor.

Further embodiments include finishing the substrate with attachmentbumps coupled to vias formed in the first dielectric layer andelectrically coupled to the diaphragm.

In further embodiments forming vias further comprises forming metal viasto the coils through the second dielectric layer. In further embodimentspatterning the second metal layer comprises patterning a photoresist,depositing a metal film and removing the photoresist to form a meshpattern. In further embodiments etching the first dielectric layercomprises applying a hard mask over the first dielectric layer andetching the dielectric through the mask. In further embodimentsattaching a magnet comprises using a cured die backing film.

Some embodiments pertain to an inertial sensor in an integrated circuitdie that includes a first patterned metal layer, a first dielectriclayer over the first patterned metal layer, a second patterned metalover the dielectric layer forming coils of an inertial sensor andconnected to the first metal layer, a second dielectric layer over thesecond metal layer, a third patterned metal layer forming further coilsof the inertial sensor and connected with a plurality of vias, and amagnet attached over the coils of the inertial sensor.

In further embodiments the second patterned metal layer is furtherconnected to other circuitry of the integrated circuit die. Furtherembodiments include vias through the first dielectric layer to connectsolder bumps of the integrated circuit die to the coils of the secondmetal layer.

Some embodiments pertain to a computing system that includes aprocessor, a memory to store instructions for execution by theprocessor, and an inertial sensor in an integrated circuit die. Theinertial sensor includes a first patterned metal layer, a firstdielectric layer over the first patterned metal layer, a secondpatterned metal over the dielectric layer forming coils of an inertialsensor and connected to the first metal layer, a second dielectric layerover the second metal layer, a third patterned metal layer formingfurther coils of the inertial sensor and connected with a plurality ofvias, and a magnet attached over the coils of the inertial sensor.

What is claimed is:
 1. A method of forming a pressure sensor in anintegrated circuit die, the method comprising: forming a releasablelayer over a removable core; forming a first dielectric layer over thereleasable layer; patterning a metal layer over the first dielectriclayer to form conductive metal paths and to form a diaphragm with thedeposited metal; forming a second dielectric layer over the metal layerand the diaphragm; forming vias through the second dielectric layer;patterning a second metal layer to connect with the formed vias and toform a metal mesh layer over the diaphragm; releasing the removable corefrom the first dielectric layer using the releasable layer; etching thefirst dielectric layer under the diaphragm to form a cavity; lining thefirst dielectric layer and the cavity with a sealing layer; covering thecavity to form a chamber adjoining the diaphragm; and sealing the coveragainst the cavity.
 2. The method of claim 1, further comprisingfinishing the substrate with attachment bumps coupled to vias formed inthe first dielectric layer and electrically coupled to the diaphragm. 3.The method of claim 1, wherein forming vias further comprises formingmetal vias to the diaphragm through the second dielectric layer.
 4. Themethod of claim 1, wherein patterning the second metal layer comprisespatterning a photoresist, depositing a metal film and removing thephotoresist to form a mesh pattern.
 5. The method of claim 1, whereinetching the first dielectric layer comprises applying a hard mask overthe first dielectric layer and etching the dielectric through the mask.6. The method of claim 1, wherein the sealing layer comprises siliconnitride.
 7. The method of claim 1, wherein the removable core comprisesan inner organic carrier, an outer copper film over the organic carrier,and wherein the releasable layer is formed over the outer copper film.8. The method of claim 1, further comprising patterning a third metallayer to connect with the formed vias and to form a second metal meshlayer over the diaphragm.
 9. The method of claim 1, further comprisingforming the first dielectric layer over a peelable substrate andremoving the diaphragm and the first dielectric layer from the peelablesubstrate after forming the metal mesh to expose the first dielectriclayer under the diaphragm before etching the first dielectric layer. 10.The method of claim 1, wherein covering the cavity comprises applyingsolder resist over the sealing layer.
 11. The method of claim 1, furthercomprising forming an inertial sensor over the releasable layer andconnecting the inertial sensor to other components of the integratedcircuit die.
 12. A pressure sensor in an integrated circuit die, thepressure sensor comprising: a first patterned metal layer to formconductive metal paths of the integrated circuit and to also form adiaphragm of the pressure sensor; a second dielectric layer over themetal layer and the diaphragm; a second metal layer over the dielectriclayer and the first patterned metal to form a metal mesh layer over thediaphragm; a first dielectric layer under the first metal layer andremoved under the diaphragm to form a cavity; a cover under the cavityto form a diaphragm chamber; and vias through the second dielectriclayer to connect the metal diaphragm and the metal mesh to externalcomponents.
 13. The pressure sensor of claim 12, wherein the chamber issealed with silicon nitride.
 14. The pressure sensor of claim 12,wherein the metal paths are coupled to other circuitry in the integratedcircuit die to relate the diaphragm movement to a pressure.
 15. Thepressure sensor of claim 12, wherein the cover comprises solder resist.16. The pressure sensor of claim 12, further comprising attachment bumpsin the die to connect to an external electrical potential, theattachment bumps being connected to the metal mesh through vias in thedie.
 17. The pressure sensor of claim 12, further comprising a thirdmetal layer to connect with the vias and to form a second metal meshlayer over the diaphragm.
 18. A computing system comprising: aprocessor; a memory to store instructions for execution by theprocessor; and a pressure sensor in an integrated circuit die of thecomputing system, the pressure sensor including a first patterned metallayer to form conductive metal paths of the integrated circuit and toalso form a diaphragm of the pressure sensor, a second dielectric layerover the metal layer and the diaphragm, a second metal layer over thedielectric layer and the first patterned metal layer to form a metalmesh layer over the diaphragm, a first dielectric layer under the firstmetal layer and removed under the diaphragm to form a cavity, a coverunder the cavity to form a diaphragm chamber, and vias through thesecond dielectric layer to connect the metal diaphragm and the metalmesh to external components
 19. The computing system of claim 18,wherein the chamber is sealed with silicon nitride.
 20. The computingsystem of claim 18, wherein the metal paths are coupled to othercircuitry in the integrated circuit die to relate the diaphragm movementto a pressure.